In current aircraft, and notably for maintenance and accessibility reasons, the computers are grouped together in electrical enclosures.
The enclosures, also called electrical or avionics racks, have three main functions. An interconnection function: to connect the computers grouped together in the enclosure between the equipment items and with the apparatus for exchanging data and electrically powering these computers.
A mechanical function: to hold the computers of the apparatus in position.
A cooling function: the system for cooling the apparatus is directly connected thereto such that cold air circulates in the shelves of the enclosure to directly cool the computers while hot air is also extracted by these shelves.
The technology used for the connections is of the electrical wiring type by means of standardized connectors (connectors known by the acronym ARINC) which are heavy and bulky.
Some links use optical fiber but these connections are few in number.
Each computer is linked to the equipment items of the aircraft by means of a standard connector for example of ARINC 600 type, that is to say a connector with 600 points of connecting and the wiring is of point-to-point type.
More often than not, all of the points of contact of the connector are not used and approximately 30 to 40% of the connection capacity of the connector is used which results in obvious loss of space, excess weight and excess cost.
Furthermore, each change of configuration of the architecture of the computer network leads to a wiring modification procedure that is difficult and costly in terms of time.
For example, for an enclosure or rack of average size for an average civilian mail airplane, the total weight of the cables, of the cable supports and of the connectors is approximately 80 kg whereas the weight of the mechanical structure is close to 70 kg. Thus, the interconnection represents more than 50% of the overall weight of the rack.
The current interconnection solutions in the aircraft are therefore mainly three-dimensional wired networks and all of the wiring is located at the computers in the electrical enclosures.
Trial production of devices for wireless communication between a number of equipment items and using waveguides exist, the document U.S. Pat. No. 8,078,215 for example proposes a waveguide solution comprising a number of points of connection and the document US2010/0318243 proposes using airplane structural parts, the stringers, as waveguide.